Organosilicon polymerizing catalyst



United States Patent 26,697 ORGANOSILICON POLYMERIZING CATALYST Donald E. McVannel, Hemlock, Mich, assignor to Dpw Corning Corporation, Midland, Mich., a corporation of Michigan No Drawing. Original No. 3,243,410, dated Ma 29, 1966,

Ser. No. 269,151, Mar. 29, 1963. Application for reissue Sept. 25, 1967, Ser. No. 677,490

Int. Cl. Clllig 31/34, 31/32 US. Cl. 260-465 7 Qlaims Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue speedication; matter printed in italics indicates the additions made by reissue.

ABSTRACT OF THE DISCLOSURE A melltod for polymerizing diorganosiloxane cyclic trimers and diorgano-silcrltylenc cyclic dimers to linear polymers having no volatile materials is accomplished by contacting the cyclic compounds with R(SM wherein R is a hydrocarbon radical of valence x and M is an alkali metal, tctraorganonirrogen radical or lctraorganophosphorus radical and x is 1 to 4.

This invention relates to a new class of catalysts for polymerizing organosilicon compounds.

There are two basic commercial methods for polymerizing organosiloxanes, One of these is by rearranging siloxane linkages. The method involves the use of a bond rearranging catalyst such as a strong alkali or a strong acid. This method is widely used commercially, but it suffers from the disadvantage that the siloxane bonds of the produced polymer can be rearranged by the same catalyst to produce the starting cyclic materials. Consequently, this mcthod inherently gives a certain portion of cyclic products in the final polymer.

The cyclic trimers of diorganosiloxanes have been found to be unique in that, under the influence of the above alk aline catalysts linear products are formed which degrade to cyclic materials (by further rearrangement) at a sulllcicntly slower rate that linear polymers can be isolated by deactivating or. preferably, removing the catalyst at the proper time. This principle of employing the trimer and deactivating the catalyst at the stated suitable time is utilized in the preparation of fluorohydrocarbon polysiloxanes, as shown in Us. Patent 3,002,95l.

The second method of polymerizing siloxanes is through the condensation of silicon-bonded hydroxyl groups. By this method, if the starting siloxane contains more than six silicon atoms, essentially no cyclic products are formed during the polymerization. (Catalysts commonly classed as rearranging catalysts also cause hydroxyl condensation, but because they also cause bond rearrangement are not normally classed with the condensation catalysts.) An example of a catalyst for condensation of silicon-bonded hydroxyl groups is given in US. Patent 2,902,468. The said catalyst has no effect on the siloxane bonds in the system other than to catalyze their formation. [It is this latter method of polymerization to which this inven tion is directed] It has also been found that certain cyclic siloxanes are caused to polymerize by the catalysts of this invention. This action is distinguished, however. by the fact that the cyclics are converted to linear polymers in an irreversible reaction. and that further no new cyclic materials are formed by the presently disClOsed catalysts. These certain cyclics arc the diorganosiloxanc cyclic trimcr and the tctraorganosilethylcnesiloxanc cyclic dimer.

[it is an object of this invention to provide a new method of polymerizing siloxanes containing silicon-bonded Re. 26,697 Reissuted Oct. 28, 15359 ice hydroxyl radicals] it is [another] an object to provide a new method of converting cyclotrisiloxanes to linear polysiloxanes. A further object is to provide a method of converting silethylenesiloxane dimer cyclics to linear silethylenesiloxane polymers. Another object is to provide a method for polymerizing siloxanes without the accom panying rearrangement of the siloxane bond to give volatile fragments. [Another object is to provide a novel method of curing siloxanes] These and other objects will become apparent from the following description.

This invention relates to a method of polymerizing organosilicon compounds which comprises contacting (I) an organosilicon compound selected from the group consisting of (a) [organosilicon compounds having an average per silicon atom of 1 to 3 inclusive substituent groups selected from the group consisting of monovalent hydrocarbon radicals, monovalent halohyclrocarbon radicals and cyanoalltyl radicals. and at least one SiOl-l group per molecule, any remaining valences of the silicon atoms of said organosilicon compound being satisfied by selection from the group consisting of divalent oxygen atoms, divalent hydrocarbon radicals, divalent hydrocarbon ether radicals containing no more than one oxygen atom therein, and haloarylene radicals, (b)] diorganosiloxanc cyclic trimers wherein the organic radicals are selected from the group consisting of monovalent hydrocarbon radicals, monovalent halohydrocarbon radicals and cyanoalkyl radicals, [(0)] (b) tfiorgano-silethylenesiloxane cyclic dimers wherein the organic radicals are selected from the group consisting of monovalent hydrocarbon and halohydrocarbon radicals, each free of aliphatic unsaturation, and cyanoalkyl radicals, and [(d)] (c) mixtures thereof with (2) a compound of the formula RtSM) wherein R is selected from the group consisting of unsubstituted and substituted hydrocarbon radicals of valence x, M is selected from the group consisting of alkali metals, tetruorganonitrogen radicals and tetraorganophosphorus radicals, the organic radicals of the said nitrogen and phosphorus radicals being monovalent hydrocarbon radicals free of aliphatic unsaturation attached directly to the said nitrogen and phospho ous atoms. and x has a value of at least one. until the desired degree of polymerization is obtained.

Component (1) can be any of the [three] two defined compositions (a) (b) and (c),] and (b) or any mixtures thereof]: Composition (a) can be made up of units of the formulae RSiO R' SiO, R' SiO various silcarbane structures such as silmethylene, silethylene, silphenylene, etc., and limited amounts of SiO- groups, wherein R is a monovalent organic radical as defined.

Component (a) can be a monomer or polymer; that is, it can contain only one silicon atom per molecule or more than one silicon atom per molecule, There can be from one to any number of silanol groups per molecule, provided the composition falls within the definition given above. Thus, for the purpose of this invention, organesilicon compound (a) can be polymeric materials such as l,i,3,3-tetramethyl 1,3 disilapropane 1,3 diol, 1.3- dimethyl-l,3-diphenyl 1,3 disiloxane 1,3 diol hydroxylated diethylsiloxane, and hydroxylated phenylmethylsiloxanes. In addition, organosilicon compound (a) can be copolymers of any of the defined organosilicon compounds such as copolymers of chlorophcnylmethylsiloxane and dimethylsiloxane; copolymers of monophenylsiloxane, phenylmethylsiloxunc and trimcthylsiloxnne and copolymcrs ol' dimcthylsilphenylcnc and phcnylmethylsiloxane. As well, orgunosilicon compound (a) can be a mixture of two or more of the defined monomers. polymers and copolymcrs.

For the purpose of this invention the monovalent hydrocarbon radicals attached to the silicon atoms of (a) can be any monovalent hydrocarbon radical such as alkyl radicals such as methyl, ethyl, isopropyl, tertiarybutyl, octadecyl or myricyl; alkenyl radicals such as vinyl, allyl, methallyl, hexenyl or butadienyl; cycloaliphatic radicals such as cyclophenyl, cyclobutyl and eyclohexenyl; aralkyl radicals such as benzyl and beta-phenylethyl; and aromatic hydrocarbon radicals such as phenyl, xcnyl, tolyl, naphthyl and anthracyl. The organosilicon compound (a) can also contain any pcrfluoroalkylcthyl radical such as 3.3.3-trifluoropropyl and C F cH CH haloaryl radicals such as tetrachlorophenyl, pentabromoxcnyl, and iodonaphthyl; and cyanoalkyl radicals such and the like.

[The divalent hydrocarbon radicals of organosilicon compound (a) can be any divalent hydrocarbon radical such as alkylene such as methylene, ethylene, hexylene and octadecylene; alkenylene radicals such as propenylene, butenylene and hexenylene; aryl radicals such as phenylene. xenylene, tolylene and naphthylene; and any divalent haloarylene radicals such as tetrachlorophenylene, dibromonaphthylene, iodotolylene and bis-(trifiuoromethyl)xenylene.]

Any diorganocyclotrisiloxane or cyclic silethylenesiloxane as described above can be polymerized by the method of this invention. Thus, for the purpose of this invention, each radical of cyclotrisiloxane (1) [(b)] (a) above can independently be as defined. The radical can be alkyl such as methyl, ethyl, butyl, octadecyl and myricyl, both straight and branched chain; unsaturated aliphatic such as vinyl, allyl, methallyl, propargyl and butadienyl; cycloaliphatic such as cyclobutyl, cyclopentyl and cyclohexadienyl; aralltyl such as bcnzyl, 2-phenylpropyl and hcnethyl', aryl such as phenyl, xenyl, naphthyl, benzylphenyl and anthracyl; and alkaryl such as tolyl, xylyl and t-butylphenyl. The radical can also be halogenated derivatives of any of the above said radicals, such as chloro methyl, brornobutenyl, dibrornocyclopentyl, a,a-difluorohcnzyl, perchlorophenyl and hexafluoroxylyl. The radical can also be any cyanoalkyl radical such as Z-cyanoethyl, Z-cyanopropyl, 4-cyanoisohexyl, and cyanooctadecyl. Generally, preferred radicals are those commercially available, including methyl, ethyl, vinyl, allyl, 2phenylpropyl, phenyl, xenyl, 3,3,4,4-pentafluorobutyl, 3.3.3 trifiuoropropyl, B- cyanoethyl and gamma-cyanopropyl.

Cyclotrisiloxane (l) [(bl] (a) can contain one, two or three different kinds of diorganosiloxane units therein. Generally, all three units are the same; these trimers are most easily prepared by the method described in US. Patent 2,979,519, which briefly comprises contacting a siloxane of the unit formula R SiO, with or without other siloxanes such as R' SiO and R'SiO (R' is a rnonovalcnt organic radical), with an alkaline catalyst and heating to distil the corresponding cyclotrisiloxane from the reaction mixture. However, there can be two or even three kinds of diorganosiloxane units in cyclotrisiloxane (l) [(b)] (a), which can be obtained by, for example, cohydrolysis or by any of several other well known procedures common to silicone chemistry. The exact method by which the cyclotrisiloxane is made is unimportant to the process of the invention.

Thus, cyclotrisiloxane (1) [(b)] (a) can be a homotrimer, a cotrimer or a mixture of homoand/or cotrirners. This is advantageous in that copolymers can be prepared by this method employing either a cocyclic trimer, i.e. one containing two or more kinds of siloxane units per trimer, or mixtures of two or more trimers, each containing a different siloxane therein. It is, of course,

obvious that each of the two R radicals on a silitam atom can be the same or different.

Silethylenesiloxane cyclic (1) [(c)] (b) can be any silethylcnesiloxane cyclic as above defined. Thus, each radical can be, for example, alkyl such as methyl, ethyl, propyl, butyl, hexyl, octyl, dodecyl, octadecyl and myricyl: cycloalkyl such as cyclobutyl, cyclopentyl and cyclohexyl; aralkyl such as benzyl, phenethyl, 2-zenylpropyl and 4- naphthyl-T-tolyldodecyl; aryl such as phenyl, rtcnyl, naphthy], anthracyl, phenanthryl, fluorenyl, naphthacenyl, pyrenyl, idenyl and acenaphthenyl; arkaryl such as tolyl, xylyl, ethylphenyl, t-butylzenyl, octadecylnaphthyl, cumenyl and durenyl; halogenated derivatives of the above such as chloromethyl, 3-chloropropyl, dibromooctadecyl, iodocyclopentyl, 3,3,3-trifluoropropyl, pentadecylfiuorononyl, 2,2-bis(trifiuoromethyl)ethyl, chlorophenyl, mmdifluorobenzyl and bis-(trifluoromethyl)phenyl; and cyanoalkyl such as 6- cyanoethyl, gamma-cyanopropyl, delta-cyanohexyl and omega-cyanooctadecyl. Generally, preferred radicals are those readily available commereially, including methyl, ethyl, cyclohexyl, phenyl and 3,3,3 -trifluoropropyl. It is preferred when the product will be used in a high temperature environment that at least one of the radicals, and most preferably two or more, be phenyl.

The preparation of these silethylenesiloxane eyclics is detailed in US. Patent 3,041,362 (Marker), and in copending application Serial No. 251,065, filed Jan. 14, 1963 (Steward), now abandoned, both references of which are hereby incorporated by reference. In the method of Steward, cyclics wherein all radicals are the same are most easily prepared, while in the Merker method each organic radical can be the same or different. Thus, each radical in this compound can be the same or dilferent, as desired. Additionally, mixtures of two or more silethylenesiloxane cyclics can be employed.

Component (1) can be any of (a) (b)] or [(or)] (b) above. Further, it can comprise more than one (a) compound, or (b) component or (c) component]. In addition, component (1) can be a mixture of one or more each of (a) and (b) one Or more each of (a) and (c), one or more each of (b) and (c), or one or more each of (a), (b) and (c) components].

Component (2) of this invention is the novel catalyst. It is an alkali salt of a thio-compound, of the formats R(SM) wherein R is an organic radical of valence x, M is an alkali metal or tetraorganoammonium or tetraorganophosphorium radical, and x is at least one.

Radical R can be monovalent hydrocarbon such as aliphatic such as methyl, ethyl, propyl, butyl, octadecyl, myricyl, vinyl, ally], methallyl, butadienyl, butenynyl and propargyl; cycloaliphatic such as cyclobutyl, cyclopentemy] and cyclohexadienyl; and aromatic such as phenyl, xenyl, naphthyl, anthracyl, pyrenyl, phenanthryl, fluorenyl, naphthacenyl, idenyl, tolyl, xylyl, t-butylxenyl, octadecylnaphthyl, cumenyl, durabuyl, benzyl, phenethyl and 4-naphthy1- 7 tolyldodecyl. Radical R can also be substituted monovalent hydrocarbon, such as halogenated, hydroxylated, aminatecl, nitrated, silylated, etc. Examples of substituted monovalent hydrocarbon radicals include a r, a z n,

CU CII ll NO1C|H( Nor-Q and (CHth slIs-QiCHgCHgClIg- Radical R can also be diand poly-vaient hydrocarbon and substituted hydrocarbon, such as -CH;CH;-,

NO: (1112- H iHn F CH IL- and CH CHzC IltClb-J;

Substituent M can be an alkali metal; it can also be a tetraorganonitrogen or tetraorganophosphorus radical wherein the said organic radicals are monovalent hydrocarbon such as methyl, ethyl, octadecyl, cyclohexyl, benzyl, phenyl and tolyl. Preferably M is sodium, lithium or potassium.

Because of the more ready availability and stability of organosulfur compounds as above containing only one sulfur therein, it is preferred that x is 1. This is not to say the x cannot be more than one, if desired; however, when x is greater than one the stability of compound (2) is reduced. Thus, preferred compounds are of the formula RSM. Most preferred are those wherein R is monovalent unsubstituted or monosubstituted, containing less than about seven carbon atoms. Examples of most preferred compounds (2) are CH CH CH CH SK,

Component (2) is prepared by reacting stoichiometric quantities of RtSH), and MOH. When the thiol is a volatile compound, this property can be put to good use to insure complete reaction of the alkali hydroxide by employing an excess of the thiol over the above said stoichiomctric amount. The reaction is best carried out in a mutual solvent for the two reactants. Water, alcohol, and water-alcohol mixtures are especially suitable solvents for the reaction, although any fluid that is a solvent for the two can be employed if desired. The said solvent serves to bring the two reactants into intimate contact and to therefore hasten the reaction. The catalyst can be recovered by evaporation of the solvent. Alternatively, it can be left in the solution in which it is prepared, if desired.

The polymerization is carried out by contacting component (l) with compound (2). Reaction proceeds at room temperature, and in many cases at a sufficient rate that heating to hasten the reaction may even be inadvisable. However, when the reaction is sluggish at room temperature, the rate can be enhanced by heating. [When organosiiicon compound (l) (a) is present, the rate can be further increased by providing a means for removing bvproduced water. This can be done by sparging, drawing a vacuum, purging the atmosphere, and, when a water-immiscible solvent is employed, by azeotroping, or by other suitable means] The polymerization can be carried out in the bulk, if desired. When so desired, it is preferred that the catalyst be one which is at least partly, and more preferably completely soluble in the siloxanes. Alternatively, the polymerization can be conducted in an organic liquid that is a solvent for the reactants, and preferably, the polymerization product. Conventionally, solvents that can be employed include hydrocarbons such as heptane, cyclohexane, methylcyclopentane, benzene, toluene, naphtha, mineral spirits and petroleum ethers; ketones such as acetone, methyiisobutyl ketone, acelophenons and bcnzr phenone; ethers such as diethylether, dibutylether, meriylarnyl ether, ethylene glycol dimethyl ether and diettzvL ene glycol diethylether; esters such as butyl acetate; haiogenated organic liquids such as chloroform, perchloro ethylene, bromobenzene, benzotrifiuoride, 2,2'-dibromodiethylether, trichlorotrifluoroacetone and propyl trichloroacetate; nitriles such as acetonitrile and benzonitrile; nitro compounds such as nitropropane and p-nitro= toluene; and compounds such as diorganosulfones and iorganosulfoxides, such as dimethylsult'one and cr'cyt propyl sulfoxide.

[When component (1) (a) is present, a solvent that is immiscible with and, preferably, azeotropes water provides in addition a handy means of removing by-produced water, when desired] Components (1) (b) and (1) [(c)] (a) produce, upon polymerization linear polymers. The presently disclosed catalyst acts on these cyclics to convert them to linear materials. The catalyst is inert to the product, so that for these-reactions, the polymerization rate can be followed by determining the rate of disappearance of the tyclics. The polymerization reaction can be stopped at any time short of completeness by deactivating or removing the catalyst. The degree of conversion will be something less than percent, and can be determined by finding the percentage of unconverted cyclic material remaining.

[Component (1) (a) can be an essentially difunctional polysiloxane, in which case its polymerization product will also be a linear or essentially linear polymer. However, this component can be other than essentially difunctional, so that products ranging from triorganosilyl end-stopped fluids to complex resinous networks can result from the polymerizations wherein there is contained some of component (1) (a) by this system. In fact, the polymerization catalyst of this invention is also a curing catalyst for systems where the functionality of the system is greater than two per silicon atom, in that rigorous polymerization will produce a cross-linked, or cured, network] [When it is desired to introduce functionality other than two into a system polymerized from components (1) (b) and/or (1) (c), this can conveniently be done by the inclusion of the desired amount of component (1) (a) that will give the said different functionality] One of the important uses for the instant mathprepare essentially linear polymers of gum g n i cosity above 5,000,000 cs.) for use in Ul'gtmUSiiicUn etastomers. For this purpose the components (l) (b) and (l) [(c)] (a) are ideally suited, as these are precisely difunctional. [There are also many sources of strictly difunctional siloxanes of the component (1) (a) type that are also admirably suited to this use, as well. However, component (1) (a) can best be used in this circumstance to supply the very desirable slight amount of endstopping for these desired gum polymers] When gums are desired it is advisable to rigorously removed moisture, either before or during the polymerization. This is, of course, true for all methods of polymerization, and the same stratagems can be employed here, such as pre-drying the components, sparging or sweeping with a dry atmosphere, and, in this method, employing such other procedures as stated above.

From the above discussion it is readily apparent that in the method of this invention component (1) can be a single kind, of mixture of one kind or mixture of one or more each of two [or three] kinds, and further that mixtures of component (I) allow an increased versatility of the polymerization process.

The process of this invention is also suitable for the preparation of fluid polysiloxanes having low amounts or no volatile fragments. [it is also suitable for the polymerization to and curing of resinous silicones that may be applied as coatings for electrical conductors or as protective coatings for wood and metal surfaces] The following examples are illustrative only and are not to be construed as limiting the invention, which is properly delineated in the appended claims.

Example 1 This example illustrates the ease of preparing the cataclosed container. Polymerization proceeded rapidly to form a high gum in three hours. which did not change after this time.

The preceding two examples illustrate the irreversibility of the polymerization reaction of this invention. When lyst of this invention.

A mixture of 39 g (0.50 mo) of monolhioglycol the cyc ic tumor of this invention s polymerized w th (SCH CHZOH) 20g (0 357 monofpotassium hydro conventional alkal ne catalysts a high polymer which ide and 100 g of methanol was placed in a reactor and results is rather quickly reverted to cyclic materlals other agitated until there was complete solution of the thiol than lfi the i l F f f g a and alkali in the methanol. The methanol, by pr0duced move 8 p0 ymels pm m y? i water and excess HSCHHCHZOH were removed by heating above were unaffected by the catalyst of this invent on, as to 100 c at a pressure of 1 mm of mercury for one shown by there being no change after polymerization (3 hour The'product (KSCHZCHZOH') was a white Solid to 4 hours) even on continued heating for a total of three Y days. ThIS was crushed to a powder for use as a catalyst. Example 6 [Example 2 A mixture of 100 g. of a hydroxyl endblocked essen Salts are formed as shown when any of the following tially dimethylpolysiloxane having a viscosity of 70 cs. thiols are reacted with the alkaline reagents as shown, at C. and 0.1 g. of the catalyst prepared in Example following the procedure of Example 1.

'Itiiol Alkaline Reagent Salt;

CmHnSH C5011 CniHnSCS (CHgCHgSH): LlOH (CHgUHzSLlh cmommcms-H), (CH:]tNOH CH CH ClCH SBHCHQJg or en s C aHzs(C NOII omcmsmcnmcnn cincnzcucmslt NaOll omclbcncnzsns CellsCHgSli RbOll CnH CU SRD S1I [CoHKCgHrhP Il] sl i znbla t l cul'lflczllghpolf CHzCH: CIlzClh rim-CH NaOH IhNCH CH; II-SH cm HSNa NO SH K011 NO SK F CH) F GE] HS --SH KOII KS SK l ILH] NU) NH; N0!

1 was heated two hours at ll0 C. with stirring at a con- Example 7 g a i g iig g f zz of of mercury A Equivalent results are obtained when any of the followf mixmre heated three hours at 180 mg reagents are used in place of methanol in Example 1: t 2000 C f 1 water, ethanol, rsopropanol, acetonttrtle, ethylene glycol, timely 1; in gg g g ig ix' fg g fi $325; dimetlfiytrtheg, dioxane, tetrahydrofuran and mixtures of completely soluble in toluene] any 0 e a Example 8 [Example 3 Polymerization occurs when any of the following mix- A mixture of 100 g. of a hydroxyl-entlblocked 3,3,3- l res are reacted as shown: trifluoropropylmethylpolysiloxane, containing 2.1 weight (a) A mixture of 100 parts of a cyclic of the formula percent of silicon-bonded hydroxyl radicals, and 0.1 g. of the catalyst of Example 2 was heated with mixing for three hours at 180 to 200 C. and 1.0 mm. pressure. The OHUZSKCHzCHzSKCB|)C H| 3 3g??? high polymer had a wmmms plasuclty of and 20 parts of C H SCs heated 20 minutes at 45 C.

' Example 4 [(b) A mixture of 90 parts of a cyclic of the formula A mixture of 20 g. of the cyclic trimer of 3,3,3-trifluoropropylmethylsiloxane and 0.02 g. of the catalyst of the C H,(CECH CHdS H B S H preceding [example] Example I was heated three days at 150 C. in a closed container. The siloxane polymer- 5 Parts of the W of slz Qf p f a ized to a thick fluid in less than four hours and underwent y y Efldblocked 300 lluld containing no further change subsequent to this time. 0 mOl p 0f s a( 3) llmtS a d 90 11101 percent of C H (CH )S1O units, 1 part of a cyclic trimer Example 5 containing two CH (CH;==CH)SiO units and one A mixture of 20 g. of the cyclic trimer of Example 4, CH3(C"H3T)S'O 0.02 g. of the catalyst of that example and 0.02 g. of calunits and 3 parts of tiscmcn cn CH SLi heated 38 Z 2 I cined calcium oxide was heated three days at 150 C. in a hours at 78 C. under a dry am] (c) A dispersion of 75 parts of (CIhh-HGIARSKCHQ;

20 parts of (ClHlhBfi-IKESKCHQ 5 parts of the cyclic trimer of phenylmethylsiloxane and 15 parts of CH CH C[CH SN(CH in 400 parts of methylcyclopentane, heated 15 minutes at reflux with azeotrope.

[(d) A dispersion of 90 parts of a hydroxylated I cs. (at 25 C.) polysiloxane containing 98 mol percent of dimethylsiloxane units and two mol percent of monophenylsiloxane units, 10 parts of the cyclic t lflmsm mtfiislrcmm and 002 part of CH =CHCH SNa in 900 parts of toluene, heated at the reflux for two hours] (e) A mixture of 3 parts the cyclic trimer of chlorophenylmethylsiloxane, 95 parts of the cyclic trimer of C F CH- CHflCH-QSiO and 0.5 part of a 2 s)a t2 2s healed 10 minutes at 135 C., sparging with dry nitrogen.

[(f) A dispersion of 3 parts of Ou n HO i011 0.2 part of a hydroxylendhlocked 40 cs. (at 25 C.) methylvinylpolysiloxane, 4 parts of a hydroxyl endblocked cyclohexylmethylpolysiloxane, 1.8 parts of diphenylsilancdiol, 6 parts of hydroxylatcd monophenylpolysiloxane, 2 parts of a hydroxyl-endblocked benzylethylpolysiloxane, 83 parts of the cyclic trimer of dimethylsiloxane and 0.05 part of C H CH SRb in M00 parts of cyclohexane, heated 4 hours at reflux with azeotrope] [Example 9 When a hydroxylated resin containing MeSiO units is heated with at least 0.01 part per hundred of resin of the resin becomes further crosslinked.

When 1 part of on. 2H6)3slCH2 lHC I;sND is substituted for the phosphorium salt above, crosslinking also results] [Example 10 When 100 parts of diphenylmethylsilanol and 0.5 parts of CH3CH1 H;NCH

CH:CHSN8 are mixed and heated at high vacuum above 100 C., the corresponding disiloxane, tetraphenyldirnethyldisiloxane is formed in excellent yield.

When 2 parts of NaSCH CI-I SLi are substituted for the thiol salt above, equivalent results are obtained] That which is claimed is:

[1. A method of polymerizing organisilicon comh pounds which comprises contacting (I) an organosilicon compound selected from the group consisting of (a) organosilicon compounds having an average per silicon atom of l to 3 inclusive subslituent groups selected from the group consistin of monovalent hydrocarbon radicals, monovalent halohydrocarbon radicals and cyanoziikyi cals, and at least one SiOH group per molecule, any remaining valences of the silicon atoms of said organosilicon compound being satisfied by selection from the group consisting of divalent oxygen atoms, divalent hydrocarbon radicals, divalent hydrocarbon ether radicals containing no more than one oxygen atom therein, and haloarylene radicals,

(b) diorganosiloxane cyclic trimers wherein the organic radicals are selected from the group consisting of monovalent hydrocarbon radicals, monovalent halohydrocarbon radicals and cyanoalkyl radicals,

(c) diorgano-silethylenesiloxane cyclic dimers wherein the organic radicals are selected from the group consisting of monovalent hydrocarbon and halohydrocarbon radicals, each tree of aliphatic unsaturation, and cyanoalltyl ratlicals, and

(d) mixtures thereof with (2) a compound of the formula R(SM) wherein R is selected from the group consisting of unsubstituted and substituted hydrocarbon radicals of valence x,

M is selected from the group consisting of alkali metals, tetraorganonitrogen radicals and tetraorganophosphorus radicals, the organic radicals of the said nitrogen and phosphorus radicals being monovalent hydrocarbon radicals free of aliphatic unsaturation attached directly to the said nitrogen and phosphorus atoms, and

x has a value of from 1 to 4 inclusive,

until the desired degree of polymerization is obtained] [2. The method of claim 1 wherein x is 1.]

[3. The method of claim 2 wherein component (2) is alkali salt of an aliphatic thioL] [4. The method of claim 3 wherein component (1) is (a).]

[5. The method of claim 4, wherein component (I) (a) has an average per silicon atom of essentially two said defined substituents groups] [6. The method of claim 3 wherein component ti} is (b).]

[7. The method of claim 3 wherein component (1) is (c).]

[8. The method of claim 3 wherein component (1) is a mixture of (a) and (13).]

[9. The method of claim 3 wherein component (1) is a mixture of (a) and (c).]

[10. The method of claim 3 wherein component (I) is a mixture of (h) and (c).]

[11. The method of claim 3 wherein component (1) is a mixture of (a), (b) and (c).]

[12. A method of polymerizing organosilicon compounds which comprises contacting (I) an organosilicon compound selected from the group consisting of (a) a hydroxylendblocked essentially diorganopolysiloxane wherein the organic groups are selected from the group consisting of monovalent hydrocarbon radicals, monovalent halohydrocarbon radicals and cyanoalkyl radicals, in which siloxane up to percent of the siloxane oxygen atoms can be replaced by organic radicals selected from the grou s consisting of divalent hydrocarbon radicals, divalent hydrocarbon ether radicals containing no more than one oxygen atom therein, and haloalkylcne radicals,

(b) diorganosiloxanc cyclic trimcrs wherein the organic radicals are selected from the group consisting of monovalcnt hydrocarbon radicals,

monovalent halohydrocatbon cyanoalkyl radicals,

(c) diorgano-silethylenesiloxane cyclic dimers, wherein the organic radicals are selected from the group consisting of monovalent hydrocarhem and halohydrocarbon radicals each free of aliphatic unsaturation, and cyanoalkyl radicals, and

(d) mixtures thereof, with (2) a compound of the formula RSM wherein R is from the group consisting of unsubstituted and substituted hydrocarbon radicals and M is an alkali metal atom,

under conditions whereby moisture is substantially excluded until an essentially linear higher polymer is obtained] 13. A method of polymerizing organosilicon compounds which comprises contacting (I) an organosilicon compound selected from the group consisting of (a) diorganosiloxane cyclic trinzers wherein the organic radicals are selected from the group consisting of monovalent hydrocarbon radicals, monovalent halohydrocarbon radicals and cyanoalkyl radicals,

(b) diorgano silethylenesiloxane cyclic dimers wherein the organic radicals are selected from the group consisting of monovalent hydrocarbon and halohydrocarbon radicals, each free of aliphatic unsataration, and cyanoalkyl radicals, and

(c) mixtures thereof with (2) a compound of the formula R(SM wherein R is selected from the group consisting of unsubstituted and substituted hydrocarbon radicals of valence x.

M is selected from the group consisting of alkali metals, tetraorganonitrogen radicals and tetraradicals and organophosphoms radicals, the organic rn i eals of the said nitrogen and PhOSPllti'l'Us radicals being monovalent hydrocarbon radicals ire-7 r 2 aliphatic unsaturation attached directly to the said nitrogen and phosphorus atoms, and x has a value of from I to 4 inclusive,

until the desired degree of polymerization is obtained.

14. The method of claim 13 wherein at is I.

15. The method of claim 14 wherein component (2) is an alkali salt of an aliphatic thiol.

16. The method of claim 15 wherein component (it is (a).

17. The method of claim 15 wherein component (1) is (b).

18. The method of claim 15 wherein component (I) is a mixture of (a) and (b).

19. The method of claim 14 wherein M is an alkali metal atom and (I) and (2) are contacted under conditions whereby moisture is substantially excluded until an essentially linear high polymer is obtained.

References Cited The following references, cited by the Examiner, are of record in the patented file of this patent or the original patent.

UNITED STATES PATENTS 2,842,520 7/1958 Polmantcer et a1. 260-465 2,983,745 5/1961 Spcier 260-465 3,002,951 10/1961 Iohannson 260-465 3,041,362. 6/1962 Merker 260-465 3,041,363 6/1962 Merker et al. 260-465 DONALD E. CZAJA, Primary Examiner M. I. MARQUIS, Assistant Examiner US. Cl. X.R. 117-135.], 148; 260-4482, 567.6, 606.5, 609 

